Such containers generally have a base and side walls (in the event of a cylindrical container then there is only a single side wall) and are formed from a mould having an interior and a core which extends into the mould. The core is said to be unsupported in the sense that the only support for the core is at one end of the mould and thereafter the core does not come in contact with the interior of the mould. The space between the core and the mould interior is the space which receives the plastic which will form the side walls and base of the container. Normally the injection point or points at which the molten plastic is injected into the mould are located in the base since this means that the marks formed at the point of injection are not visible when the container is upright in its normal condition.
Normally during the moulding process, the flow of plastic into the mould is not exactly even in all directions and thus molten plastic flows more to one side of the core than the other. As a consequence of this uneven flow the core deforms slightly so as to bend away from the side which has the more plastic and towards the side which has the less plastic. The consequence of this is that the moulded plastics container has side wall(s) which are not exactly uniform.
This lack of uniformity is generally only visible by holding the container up to the light and observing the light transmission through the side walls of the container. The thinner portions of the wall are naturally lighter in color since they transmit more light than the thicker portions of the wall.
For most containers this small difference in wall thickness, typically a very small fraction of a millimeter, is of no consequence to the operation of the container and is easily tolerated as a non-consequential manufacturing defect.
However, a particular class of container, known as “sharps” containers are intended for the disposal of syringes which have extremely sharp needle points. Examples of such containers are those illustrated in Australian Patent No. 741,793 and in the first four drawings of the present specification. Such containers may or may not have an interior partition which divides the container into two, namely one compartment containing unused syringes and the other compartment containing used syringes.
Outside of the hospital and medical systems, there are two types of persons who regularly use syringes for the self-administration of drugs. These are essentially diabetics and intravenous drug addicts. Diabetics are insulin-dependent and require a regular injection of insulin in order to maintain their blood sugar levels. Intravenous drug addicts are dependent upon a drug such as heroin and regularly inject themselves in order to maintain a sense of euphoria.
Both classes of persons carry syringes about them from place to place and thus require a portable means of safe disposal of the syringes after the injection has taken place. For diabetics this is relatively straight forward since the syringes are not in themselves normally infected and thus it is a matter of preventing the needle tip from puncturing anything or anybody.
However, for intravenous drug users, there is a high likelihood that the syringe is infected with either Hepatitis C or HIV AIDS, or both, and thus members of the general public should be protected from the possibility of needle stick injury which may result in permanent and even fatal infection.
It is therefore highly desirable from a public health point of view that intravenous drug users not leave infected syringes lying about in public places such as parks, beaches, and the like where they can be accidentally stepped upon by members of the general public. Thus it is desirable from a public health point of view that intravenous drug users, as well is diabetics, be able to safely dispose of syringes after they have been used. Thus there is a need for an inexpensive portable used syringe container device.
Furthermore, modern and more enlightened public health policy is to prevent, as much as possible, intravenous drug users from sharing needles since this can prevent the spread of Hepatitis C and HIV AIDS. It is therefore desirable that used syringe container devices have a one-way locking arrangement which prevents used syringes once they are inserted in the container, from then being extracted from the container for re-use.
In addition, many intravenous drug users are eventually able to resist and overcome their addiction. Thus if they can be maintained healthy by not contracting Hepatitis C or HIV AIDS whilst they are addicted, this can greatly assist their eventual recovery.
Another aspect of public health is the need to protect the health of sanitary workers such as garbage collectors who may accidentally, or who may routinely be required to, come into contact with such used syringe container devices. Thus there is a desirable public health outcome if such used syringe containers are able to withstand moderate force and thus can retain the point of the needle within the container. In this way, the incidence of needle stick injuries, even of gloved hands, can be lessened.
It has been observed by the present inventors that when such sharps containers are crushed, for example, by garbage compacting devices, there is a propensity for the needle points of the used syringes disposed of therein to penetrate the side walls at those locations where the side walls are the thinnest. Another situation where such containers may be crushed is when seat belt wearing motorists carry such containers in a breast pocket and under a seat belt prior to a motor vehicle accident.